PGRS

Question 1

Dehydrins are proteins that accumulate in seeds during the later stages of their development or maturation. Their accumulation is stimulated by the plant hormone called ______.

Answer 1

ABA

Question 2

Accumulation of dehydrins allows seeds to tolerate _____ because dehydrins are highly _____ which helps maintain the adequate amount of ______.

Answer 2

dehydration tolerance; hydrophilic; water

Question 3

What is “crown gall” of plants?

Answer 3

it is a tumor on plants

Question 4

how does Agrobacterium cause crown gall

Answer 4

it tricks the plant cells into playing a host for the bacteria

Question 5

what are the steps of crown gall formation

Answer 5

1. bacteria infects the crown cells
2. transfers its genes into plant cell’s DNA (trick)
3. infected cells provide an expanding for bacteria to thrive

Question 6

Cytokinins

Answer 6

B. promote axilary branching in tissue cultures and delay senescence of leaves

Question 7

As dormant seeds come out of dormancy as a result of “moist-chilling” exposure, following happens to the levels of the two hormones:

Answer 7

B. GA, a growth promoter, accumulates while ABA, a growth retardant decreases

Question 8

Define VIVIPARY

Answer 8

a phenomenon where seeds precociously germinate

Question 9

why does VIVIPARY occur

Answer 9

it is a genetic mutation and when it has been found in corn there is a reduced production of ABA

Question 10

many PGRs are used in commercial hort as sprays/drench application to regulate plant height. they do so by:

Answer 10

inhibiting GA production

Question 11

a growth regulator that is often used as a spray on grape clusters to achieve

Answer 11

larger fruit

Question 12

the regulator used in grape clusters does so by

Answer 12

Pro-Gibbs elongate the flower stalks and spreads the flowers out and it allows for larger fruit development

Question 13

treatment of shade trees with Paclobutrazol not only controls their height but often results in darker green leaves compared to untreated ones. Give one bio chem explanation of this

Answer 13

because there are smaller cells there are more cells per unit area. this means there are also greener leaves

Question 14

GA application promotes

Answer 14

maleness

Question 15

list all steps in the mechanism of stomate closure involving ABA

Answer 15

1. ABA enters guard cells
2. loss of K+
3. water flows out of guard cells to maintain equilibrium
4. Loss of turgor-pressure in guard cells
5. Stomata close

Question 16

which hormone plays an important role in apical dominance and how

Answer 16

auxin inhibits the axillary branching by overcoming the effects of cytokinin

Question 17

what is witches broom

Answer 17

extreme axillary branching; apical dominance is countered but the lateral buds go crazy as well

Question 18

what is the hormonal explanation for witches brooming

Answer 18

overproduction of cytokinins that out competes the auxins that would promote apical dominance

Question 19

provides steps of why GA plays important role in food mobilization during seed germination

Answer 19

1. GA synthesized in the embryo after imbibition
2. diffuses to aleurone and stimulates (roman)a-amylase enzyme
3. a-amylase activated and released in endosperm
4. breakdown of starch by a-amylase
5. sugars mobilized to meet the demand by germinating seed

Question 20

PGR that mimics what hormone sprayed on grapes

Answer 20

Gibberelin

Question 21

what PGR mimics gibberelins and is sprayed on grapes

Answer 21

PRO-GIBB

Question 22

what hormone promoted maleness

Answer 22

GA

Question 23

Green revolution bonus

Answer 23

Norman Borlaug used mutated DELLA protein to promote dwarfism in wheat. The mutated DELLA is not usually recognized by GA which usually degrades it and promotes growth. This prevented lodging in wheat which resulted in the loss of seeds before harvest. He won a nobel prize for this work